<ul id="comments_list">
<?php
    $i = 0;
    foreach ($this->comments as $comment) {
        $parity = ($i % 2) ? "impair" : "pair";
        echo '<li>';
        echo "<p class=\"comments $parity\">" . nl2br($comment->content()) . "</p>";
        echo "<p class=\"signature $parity\">" . $comment->user()->login() . "</p>";
        echo '</li>';
        $i++;
    }
?>
</ul>